The present invention relates to a computer workstation, preferably for use with a computer network such as a Local Area Network (LAN) and to a computer network incorporating such a workstation. The invention relates particularly to enabling initial program load into the working memory of such a workstation.
With current technology, the main working memory of a computer workstation such as a personal computer is volatile. In other words, the memory does not retain the information stored therein when the computer is turned off. As a result of this, one of the first operations to be performed when a computer is turned on is to load initial programs into the working memory to provide the basic tools and utilities which define the operations of the computer workstation. Such initial programs include the Basic Input/Output System (BIOS), the operating system for the computer and particular applications defined by initialization control information.
In early personal computers, the initial programs were loaded into the memory from a cassette tape. However, in more recent personal computers, the initial program load (IPL) occurs from a diskette drive, either from a floppy disk (usually called the "A" drive) or from a fixed, or hard disk (usually called the "C" drive). The initialization control information which causes the IPL comprises Power On Self Test (POST) code, IPL control logic (often termed the boot record) and control data. The POST code can be stored in read only memory, or it can, at least in part, be hardwired in the computer. When the computer is powered up, the POST code tests the status of the computer subsystems and then passes control to the boot record, which usually held on a diskette medium in a stand alone computer. The control data, which is used by the POST and boot record, can be stored in non-volatile read/write memory such as CMOS memory.
In a conventional stand alone personal computer, the POST code interrogates the floppy disk drive to test whether the drive contains a bootable diskette (i.e. whether a diskette is present and whether a valid boot record is held thereon). If it does, then the boot record on the diskette is used to control the initialization of the system. If there is not a bootable diskette in the floppy disk drive, then POST reverts to the hard disk drive for the boot record. In either case, the boot record causes the loading the initial programs into the personal computer's working memory from the "A" or "C" disk as appropriate. If no boot record is found in either source, control reverts to a BASIC ROM module in the personal computer.
If a personal computer workstation is provided with a suitable adapter and connected to a computer network such as a LAN there can be another potential source for the IPL operation. Indeed, in the case of a medialess workstation (i.e. a personal computer without diskette or tape drives) connected to a LAN by means of a LAN adapter, the only source of IPL is the LAN itself. In some cases it may be possible to upgrade a medialess personal computer to include a floppy or fixed diskette drive. There is a need, therefore for a secure mechanism for determining the source of an IPL for personal computer workstation which is suitable for or may be adapted to work with a LAN or other network.
A disclosure, entitled "Dual Function ROM that Controls the Initial Program Load (IPL)", published in International Technology Disclosures (ITD), Vol. 7, No. 12, 25 December 1989 as disclosure number 128901, describes a process which allows IPL in a personal computer from an internal diskette medium, or alternatively from a local area network server or other communications medium. Decision making paths and set-up code are provided in the routines of ROM control microcode for determining the IPL source. A non-volatile memory in the computer contains option and set-up information including a Remote IPL (RIPL) Enable Flag which can be set by the operator of the computer. When the computer is powered up, a Power On Self Test (POST) program stored in read only memory interrogates this RIPL Enable Flag and tests for the presence of any local and/or remote IPL devices, and for the status of all computer subsystems. The IPL operations occur in accordance with the results of the tests performed by the POST program. The POST program contains default information which enables a medialess personal computer to be initialized.
The ITD disclosure describes a process which allows IPL in a personal computer or workstation from an internal diskette medium, or alternatively from a local area network server or other communications medium. It appears that the process is also applicable where the personal computer is medialess. However, it does not describe how the IPL operation can be made secure. There is a need in a network environment, especially a LAN environment, to ensure that the default IPL is a remote IPL.